The penalty points scandal is to be examined by the spending watchdog, it has been revealed.

The Public Accounts Committee (PAC) said it planned to analyse information from a whistle-blower who alleged the widespread cancellation of penalty points by officers.

Members want to examine the controls, protocols, procedures and systems in place in the penalty point system and, in particular, the system in place for the cancellation of penalty points.

The issue of Garda discretion in wiping driving offences was at the centre of controversy over the fixed penalty system.

Chairman John McGuinness said the committee was entitled under law to receive and use the information received.

"The information received from the whistle-blower will, for legal reasons, be anonymised and thereafter analysed in order that the committee can fully examine the penalty point system," he said.

"The committee wants to ensure that the appropriate controls are in place in relation to the cancellation of penalty points as any weaknesses in the system could potentially result in a significant loss of revenue to the state."

The committee - which is due to take evidence in public from the Garda Commissioner Martin Callinan on January 23 - will also examine a report from the Comptroller and Auditor General on the issue.

This revealed that as many as one in five drivers were evading fines because of weaknesses in the fixed penalty system.

It also found there was no apparent reason for quashing the penalties in 4% of cases, while more than half of the cases were cleared for "discretionary" reasons.